Motion compensating hoist

ABSTRACT

A motion compensating hoist for moving a load between relatively vertically movable points, in which a cable from a tensioning hoist is interconnected between the two points, and the cable from a load hoist is connected to the load, and the tensioning hoist and the load hoist are cooperable to establish movement of the load corresponding to the relative movement between the two points and to cause further movement of the load between the two points.

United States Patent Barron et al.

[54] MOTION COMPENSATING HOI ST [72] Inventors: Charles D. Barron,Huntington Beach; Earl A. Peterson, Long Beach; Gary K. Stark, BuenaPark; Carl A. Wllms, La

Habra, all of Calif. [73] Assignee: Byron Jackson, lne., Long Beach,Calif. 22 Filed: March 16, 1970 2i App]. No.: 19,582

[52] U.S.Cl ..254/l72,2l4/l4 [5 l Int. Cl ..B65g 67/58 [58]Fieldol'Search ..2l4/l3l5;

55 References Cited UNITED STATES PATENTS 1,999,936 4/1935 Lange..2s4/172 51 July 11,1972

2,293,936 8/ l 942 Crooke ..254/l 72 2,609, l 81 9/ l 952 .laeschke..254/ l 72 2,854, l 54 9/ l 958 Hepinstall.... ..2 14/ I 4 2,945,6757/l960 Fischer ..254/l 73 X Primary Examiner-Albert .I. Makay AssistantExaminer-Frank E. Werner Attorney-Donald W. Banner, William S. McCurryand John W. Butcher [.57] ABSTRACT A motion compensating hoist formoving a load between relatively vertically movable points, in which acable from a tensioning hoist is interconnected between the two points,and the cable from a load hoist is connected to the load, and thetensioning hoist and the load hoist are cooperable to establish movementof the load corresponding to the relative movement between the twopoints and to cause further movement of the load between the two points.

17 Claims, 5 Drawing figures PKTENTEDJUL 1 1 I972 sum 1 BF 4 INVENTORQ.

ATTOE/VGY PKTENTEDJUL H 1972 3,675,900

SHEET '3 GF 4 Y 465 a mew/v 6A a A. P676290A/ eAey/a 57, 125 ma A. W/AM5INVENTORS.

A TTOZ/VEV BACKGROUND OF THE INVENTION In the transfer of a load betweentwo relatively movable points, such as the transfer of cargo orpersonnel between a well drilling platform or barge which is located ina body of water and a vessel floating in the water along side theplatform or barge, problems are encountered caused by the rise and fallof the vessel on the surface of the water. When the water is rough, theproblem is aggravated. Essentially, the problem involves the difficultyencountered in moving the load, such as the cargo or personnel, througha comparatively short distance to and from the rising and falling deckof the vessel. In many instances, the transfer of equipment or personnelbetween a floating vessel and a stationary platform or larger floatingvessel in the water has heretofore been practically impossible toaccomplish in the presence of large waves, particularly when the wavesoccur at rapid intervals.

SUMMARY OF THE INVENTION The present invention provides a motioncompensating hoist system which obviates the difficulties heretoforeencountered in the movement of cargo or personnel between a platform orbarge or large floating vessel and a smaller floating vessel or boat.

More particularly, the invention provides a motion compensating hoistsystem whereby a load to be transferred between the platform and theboat is caused to move synchronously with the boat during the periodthat the load is being initially moved from or finally placed upon theboat. In accomplishing the foregoing, synchronous movement of the loadwith the boat is accomplished by a unique combination of a tensioninghoist coupled to a load hoist.

More particularly, an elevator device adapted to be connected to theload or to contain the load is carried by the load hoist line or cableand a tensioning hoist line or cableis connected to the boat. Thetensioning hoist is driven through a clutch which is adapted toconstantly slip with a given variable torque output so as to maintain asubstantially constant tension on the tensioning hoist line extendingbetween the boat and the platform. Load sensing means are responsive tothe tension on the tensioning hoist line to provide a continuous signalwhich is compared to a preset load value to automatically adjust thetorque capacity of the clutch and thereby maintain tension on the hoistline at substantially the preset value. The load hoist is connected bydrive means to the tensioning hoist and such drive means are selectivelyoperable to establish unitized drive of the tension hoist and the loadhoist, resulting in the synchronous movement of the load with the boat,and means are provided to super-impose on the synchronous movementcontrolled raising or lowering of the load from or to the deck of thevessel.

Such a motion compensating hoist system enables the effective transferof cargo and personnel between a platform and a floating boat or vesselin a much safer manner than has been heretofore proposed. Since the loadis synchronously moving with the boat, the load experiences no hardlandings or impact with the boat as the load is moved to or from theboat, and the tensioning line or cable which connects the boat to theplatform is available for use as a guide for the load to direct themovement of the load to or from a precise location on the boat, as wellas to prevent spinning of the load.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of a fomtin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense, since thescope of the invention is best defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective, fragmentaryview, showing a platform or barge above the water and equipped with theinvention for moving a load to or from a boat afloat in the water;

FIG. 2 is an end elevation of the power unit and the hoist and tensionwinches;

FIG. 3a is a fragmentary view in side elevation, as taken on the line3-3 of FIG. 2, man enlarged scale, and showing the tension winch, withparts broken away;

FIG. 3b is a fragmentary view, as taken on the line 3-3 of FIG. 2,constituting a continuation of FIG. 3a, and showing the hoist winch andits drive connection to the tension winch; and

FIG. 4 is a diagrammatic illustration of the combined winches andcontrol means therefor.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. I and2, there is generally illustrated a barge 01' platform P adapted to besupported above the water on a number of suitably located legs L whichextend to the bottom of the water, and on which the platform or barge Pis mounted. In the case of certain barges, the platform is adapted to beelevated to a selected height above the water on the legs L, a distanceof feet more or less. On the barge or platform may be located the usualwell drilling and/or completion or workover apparatus (not shown), as iswell known in the art. It will also be understood that the platform Pmay consist of a large vessel afloat on the water.

Periodically, the workers on the platform must be transported betweenthe platform and the shore, and in addition, it becomes necessary fromtime to time to move various gear between the shore and the platform.Thus, a boat or vessel V is in part illustrated, and such boats orvessels range considerably in size from comparatively large work boatsadapted to move heavy gear and supplies between the shore and theplatform, and small personnel carrying boats. In either case, problemsare experienced in transferring the gear or personnel between the vesseland the platform.

When the weather is fair and the water is calm the problem is lesspronounced, but, when the water becomes rough and swells tend to causethe boat or vessel V to rise and fall relative to the platform, theproblem is more pronounced. The 1 greater the frequency of the swellsthe worse the problem, so that under many commonly encounteredconditions, the transfer of equipment or personnel between the platformand the boat or vessel V is very difficult, if TH, V and not impossibleto accomplish.

The present invention contemplates a motion compensating hoist systemwhereby an elevator E or other load support is adapted to be raised orlowered between the outer extremity of a boom B and the vessel V, theelevator E being suspended by a load hoist cable or line 10. Atensioning line or cable 1I extends between the outer extremity of theboom B and a point of attachment 12 to the deck of the boat or vessel V.The lines or cables 10 and II respectively, are controlled by loadhoistmeans LH and tensioning hoist means the whereby during the initialstages of the lifting of the elevator E from the deck of the vessel Vandduring the final stages of movement of the elevator E onto the deck ofthe vessel V, the elevator is caused to move synchronously with thevertical movement of the vessel V, i.e., the elevator E moves in thesame direction and at the same rate that the vessel V moves, as thevessel V is subjected to wave action. Superimposed on the synchronousmovement'of the elevator E with the vessel V is independent movement ofthe elevator E in a controlled manner whereby the elevator E ismovedsmoothly and gently to or from the deck of the vessel V by the loadhoist means LI-I. The load hoist means LH is also operable, when theelevator E is moving through the portion of its travel safely above thedeck of the vessel V to independently cause vertical traverse of theelevator E. v

More particularly, the boom B is mounted on suitable support structure13 which is affixed to a side of the platform P. The boom comprises inthe illustrative embodiment a pair of laterally spaced outwardlyconvergent V-shaped arms 14 and 15, which are preferably fabricated fromupper and lower rails 16 and 17 reinforced by suitable struts 18 forrigidity, the arms 14 and being suitably connected to the supportstructure 13. Also supported on the support structure 13 is a power unitplatform 20 on which is mounted a power source 21 such as an engineadapted through a suitable reduction gear box 22 and a chain drive 23,by way of illustration, to drive the hoist means consisting of thetensioning hoist means TH and the load hoist means LI-I previouslyreferred to. At a suitable elevated and laterally displaced positionrelative to the support structure 13 is mounted a control cab C in whichan operator has good vision of the hoisting operations. Located betweenthe boom arms 14 and 15 and extending from the support structure 13horizontally to a location below the outer extremity of the boom B is awalkway W, having a laterally enlarged loading deck 26 at its outerextremity. The walkway W, the power unit platform 20, as well as thebarge or platform P are all provided with suitable guard railsthereabout, and a stairway 27 leads between the deck of the platform orbarge P and the power unit platform 20.

The load hoist line or cable 10 extends from the load hoist means LHover an inner sheave 28 which is appropriately rotatably supported overthe load hoist means LH, and extends outwardly of the boom B and overthe outer sheave 29 which is rotatably supported at the outer extremityof the boom B. A hook or other load supporting means 30 is connected tothe elevator E or other load so as to raise and lower the latter: Thetensioning line 11 leads from the tensioning hoist means Tl-I over asheave 31, then along the boom B and over an. outer sheave 34 which isrotatably supported at the outer extremity of the boom B. The tensioningline 11 extends downwardly from the sheave 34 and is provided with ahook 35 or other suitable means adapted to effect the connection of thetensioning line 11 to the vessel V at the location 12 previouslyreferred to.

The elevator E comprises a floor 36 having a cage structure 37 extendingupwardly therefrom and connected to the top 38 of the elevator, the tophaving reinforced support members 39 connected to the hook 30 centrallyof the elevator E. At one side, the elevator E has a tubular guide 40extending vertically and through which the tensioning line 11 extends.Thus, the elevator is prevented from swinging or spinning on the hoistline or cable 10, and the location on the deck of the vessel V at whichelevator E will land is established, notwithstanding any tendency of thevessel V to move in any direction away from a location directly beneaththe outer end of the boom B.

Referring to FIGS. 3A and 3B, it will be seen that the sup portstructure for the hoist means includes three laterally spaced uprightsor posts 41, 42 and 43. The uprights 41 and 42 have mounted thereon apair of laterally spaced bearing blocks 41a and 42a in which isrotatably journalled a horizontally extended tensioning hoist shaft 44.The tensioning hoist means TH includes a drum 45 on which the tensioningline or cable 11 is wound, the hub 46 of the drum 45 being keyed as at47 to the shaft 44 for rotation therewith. The shaft 44 extends throughthe bearing block 410 to provide a driven shaft end 48 adapted to bedriven by the drive means 23 under the control of slip clutch means SC.

More particularly, the drive means 23 includes a drive chain 49 adaptedto be driven by the output sprocket (not shown) of the reduction gearbox 22 of the power source 21. This chain 49 is engaged with a sprocket50, the hub 51 of which is rotatably mounted on the shaft end 48 bybearings 52. Affixed to the sprocket 50, is a disc 54 which is in turnaffixed by fasteners 55 to the outer periphery of the back-up plate 56of the slip clutch means SC.

This slip clutch means SC includes an outer annular body 57 to which anannular flange 58 is connected by fasteners 59in opposed relation to theplate 56. Internally thereof, the body 57 has a splined connection 60with the outer periphery of an axially shiftable clutch pressure plate61. Between the clutch plates 56 and 61 is a clutch friction disc 62having friction facing 63 on opposite sides thereof and having, as at64, a splined connection with a hub 65 which is disposed upon the shaftend 48 and is keyed thereto by a key 66. Thus, rotation from thesprocket 50 will be transmitted to the tensioning hoist shaft 44 whenthe slip clutch means SC is engaged to transmit rotation from the clutchbody 57 and its plates 56 and 61 to the friction disc 62.

Engagement of the slip clutch means SC is accomplished by an annularexpansible actuator tube 67 having an air inlet 68. The actuator tube 67engages an annular body of insulating material 69 interposed between thetube 67 and the clutch pressure plate 61. Each of the clutch plates 56and 61 has a number of annular radially spaced and concentric coolantpassages 56a and 61a to which a coolant is supplied to dissipate theheat of friction caused by slippage of the clutch SC These passages 56aand 610 are defined respectively between the clutch plates and a weardisc 56b carried by the plate 56 and a wear disc 61b carried by theplate 61, the friction material on the friction disc 62 being engagedwith the wear discs 56b, 61b. I

Such cooled, slip clutches are well known, and generally are providedwith a coolant circulating system including a stationary coolantconnector member 71 through which coolant flows to and from a rotaryconnector member 72 which is connected, as by fasteners 72a, to theclutch flange 58 and which has conduit means 73 and supplying coolant tothe passages 56a and 61a, as well as conduit means for the return flowof coolant to the stationary coolant connector 71 and thence to a heatexchanger. In addition, the rotary connector member 72 provides aconnection for air conduit means 74 which leads to the air inlet 68 forthe clutch actuator tube 67 from a stationary air inlet fitting 75. Asis well known, the torque transmitting capacity of such slip clutchesvaries with the pressure of air in the actuator tube 67.

Preferably, the slip clutch means SC is made in accordance with thedisclosure of U. S. patent application Ser. No. 19,601, filed Mar. 16,1970, in the name of C. D. Barron, so that the clutch plates and discsare more effectively cooled.

Referring to FIG. 3B, it will be seen that motion compensating drivemeans MC are adapted to selectively drivingly connect the shaft 44 ofthe tensioning hoist means TH to a shaft of the load hoist means LH.This shaft 80 is mounted for rotation in bearing blocks 42b and 43bwhich are mounted on the supports 42 and 43 so that the shaft 80 extendsin parallel relation to the shaft 44 in laterally spaced relation. Itwill be understood that the relationship between the tensioning hoistmeans and the load hoist means is only illustrative of a preferredarrangement under given conditions, but that the shafts 44 and 80 may beco-axially or otherwise arranged.

More particularly, the motion compensating drive means MC comprises aclutch assembly 81 including an adaptor sleeve 82 which is keyed, as at83, to the shaft 44 for rotation therewith. Typically, the clutchassembly 81 also includes a plurality of clutch discs 84. Alternatediscs 84 are splined to the adaptor sleeve 82, and the other discs 84are splined to an annular clutch body 85, whereby rotation istransmitted to the body 85 from the shaft 44 when the discs 84 areengaged between the usual back-up plate 86 and the shiftable pressureplate 87. In order to engage the clutch discs 84 between the plates 86and 87, actuator means responsive to fluid pressure are providedincluding a thrust bearing 88 which is engaged with the pressure plate87 to shift the latter towards the backup plate 86 in response tocorresponding movement of an outer actuator sleeve 89 which also isengageable with the thrust bearing 88. This actuator sleeve is slidableon a fixed actuator sleeve 90 within which the adaptor sleeve isrotatable, the sleeve 90 being secured by fasteners 90a to a suitablehousing 90b which is connected to the support 42 and shrouds the motioncompensating drive means MC. These actuator sleeves 89 and 90 aresuitably formed and sealed to provide a pressure chamber 91 to whichfluid, such as air, may be admitted through a connection 92 to effectengagement of the clutch 81.

Suitably mounted on the driven clutch body 85, as by fasteners 93, is asprocket 94. A drive chain 95 is engaged with the sprocket 94 and with asimilar sprocket 96 which is suitably affixed to the end 97 of the lifthoist shaft 80, as by a key 97a, whereby the shaft 80 will be driven bythe tensioning hoist means TH when the releasable connection provided bythe clutch 81 is engaged. Such rotation of the shaft 80 is adapted tocause operation of the load hoist means LH synchronously with thetensioning hoist means TH, during the initial stage of movement of theelevator E from the deck of the vessel V and during the final stage ofmovement of the elevator E towards the deck of the vessel.

In the preferred construction, the load hoist means is so arranged thatthe motor means for raising and lowering the load when the motioncompensating drive means MC is disconnected is also operable when themotion compensating drive means is connected, whereby to superimpose onthe synchronous movement of the load with the vessel V, further movementto move the load relative to the vessel. The load hoist means LH,therefore, includes a drum 100, corresponding to the drum 45 of thetensioning hoist means TH, and the load hoist line is wound on this drum100. Support flanges 101 are provided within the drum 100, these flangesbeing connected to or having formed at their inner periphery bearingrings 102 engageable with bearing assemblies 103, whereby the drum 100is rotatably supported on the shaft 80 so as to be rotatable relative tothe shaft. At one end of the drum 100 is the usual brake drum or flange104 with which winch drums are provided. In the present case however,the flange 104 is modified internally to provide internal gear teeth105. These teeth 105 provide for connecting both reversible hydraulicmotor means 106 and normally engaged brake means 107 to the drum 100.Such motor means 106 and brake means 107 are both carried by a plate 108which is mounted at its inner periphery on the shaft 80, a key 109 beingprovided to cause rotation of the plate 108 with the motor means 106 andbrake means 107 in the direction and at the rate of the shaft 80, thedirection and rate of rotation of which is a function of the directionand rate of rotation of the tension hoist means shaft 44.

More particularly, the motor means 106 includes a housing 110 connectedby fasteners 110a to the plate 108 and an output shaft 111 which extendsthrough the plate 108. On the output shaft 111 is a pinion 112 which isdrivingly in mesh with the internal gear teeth 105 of the drum flange104. Fluid is supplied to the motor 106 in a selected direction throughconduits 113 and 1 14 to effect reverse operation of the motor, suchfluid being supplied through passages 113a and 114a which extendlongitudinally in the shaft 80 and are supplied from stationary sourceconduits 11312 and 114b, respectively, which are connected to a rotaryfluid connector 115 suitably mounted in the housing 90b, as by fasteners116. Such a rotary connector 115 is common and requires no furtherspecific discussion. The motor 106 also has a fluid outlet 117 which, aswill be more fully described hereinafter, supplies fluid to the inletconduit 118 of the brake means 107 to release the latter when the motor106 is operating, whereby the drum 100 is revolvable about the drumshaft 80 in addition to being revolvable with the shaft 80. When themotor means 106 is operating, the net rotary motion of the drum 100, isa function of the direction and extent of rotation of the shaft modifiedby the direction and extent of rotation of the drum 100 about the shaftin either direction. Therefore, the load hoist line 10 and the elevatormay be raised or lowered by the motor 106, while the hoist line is alsomoving the elevator E in unison with movement of the boat or vessel V.

The brake means 107 comprises a housing 120 secured to the plate 108 soas to revolve with the shaft 80. Carried by and rotatably disposed inthe housing 120 is a shaft 121. This shaft 121 extends through the plate108 and has a pinion gear 122 keyed thereon as at 122a, the shaft beingjoumalled in bearings 123 within the housing 120. A rotary brake member124 is secured on the shaft 121 for rotation therewith by a key 125.Friction discs 126 are interposed between the brake rotor 124 and anactuator member 127, alternate discs being splined to the rotor 124 andto the housing 127, so that when the discs are engaged, the rotor 124will be held stationary, thereby holding the pinion 122 againstrotation, to brake the hoist drum 100. The brake 107 is normally engagedby a number of coiled compression springs 128 spaced circumferentiallyof the actuator member 127 and acting on the same and on an internalflange 129 in the housing 120 to bias the member 127 in a brake-engagingdirection. To disengage the brake means 107, fluid under pressure issupplied from the conduit 118 to a sealed piston chamber 130 in which isa piston 131 connected to the actuator member 127, as by screws 132, tomove the actuator member 127 to a brakerelease position. When the brakemeans 107 is engaged, the hoist drum 100 is effectively connected to theshaft 80 for rotation therewith, but when the brake means 107 isreleased, the motor means 106 is effective to not only connect the drum100 to the shaft 80, but also to effect relative rotation thereof, aspreviously described.

The load hoist means LH also includes brake means 135 for holding theshaft 80 stationary when the motion compensating drive clutch means 81is disengaged, during the periods that I the elevator E is high enoughabove the boat or vessel V as to be safely raised or lowered by themotor means 106, without compensating for relative movement of the boatbeneath the boom.

Such brake means includes a rotor 136 keyed, as at 137, to the outerextremity of the hoist shaft 80, and a stationary brake housing 137connected to the support 43 by fasteners 139. Friction discs 140 areinterposed between the rotor 136 and an actuator 141, alternate discsbeing splined to the rotor 136 and to the housing 138. A number ofcircumferentially spaced springs 142 are interposed between the ac--sealed piston chamber 145 acts on a piston 146, which is connected tothe member 141 by fasteners 147, to move the member to a brake-releasedposition, when, as will be later described, fluid under pressure issupplied to the piston chamber 91 of the motion compensating driveclutch means 81 to engage the latter to rotate the drum shaft 80synchronously with the tensioning hoist drum shaft 44. While the brakemeans 135 is shown as being spring set and pressure released, the brakemeans may be of the type adapted to be engaged by fluid pressure. Thesignificant point is that the brake means 135 is released when theclutch means 81 is engaged, and vice-versa, as will be later described.

OPERATION The operation of the load compensating hoist system will befurther understood with reference to FIG. 4, wherein the apparatus isschematically illustrated together with operating and control meanstherefor.

In this view, it will be noted that air under pressure is supplied tothe inlet connector 75 of the slip clutch means SC through controller orpressure regulator R1, so that the slip clutch means may be adjusted totransmit sufficient torque to the drum shaft 44 as to maintain apredetermined tension on the tension line 11 of the tension hoist meansTH which is connected to the vessel V. The controller R1 needs nospecific illustration but is preferably of the type that will cause anoutlet pressure which is a function of a SET POlNT" signal and a signalderived from tension on the tension line 10. The line tension on thetension hoist TH is selected so as to be proportionate to the total loadrepresented by the elevator E, namely, the weight of the elevator Etogether with the weight of the load to be carried in the elevator, andinertia forces to be overcome in accelerating the load when the systemis compensating for movement of the vessel V.

In order to cause motion compensating motion of the load line 10,whether or not it is connected to a load or to the elevator, the clutchmeans 81 of the motion compensating drive MC is engaged and the brakemeans 135 for the load hoist shaft is released. This is accomplished inthe case of a spring loaded brake means 135 by a control valve CV1 whichis interposed between a suitable source of air under pressure and thepressure conduits 92 and 141, the valve CV1 being operable in oneposition to connect the air supply to both the clutch means 81 to engagethe same and the brake means 135 to release the same, and conversely, inthe other position, to exhaust the clutch and brake to allow release andengagement thereof, respectively. Thus, with the clutch means 81engaged, the drum shaft 80 will rotate in the same direction and at thesame rate as the tension hoist drum 45, as the latter is caused,alternately, to turn in one direction by the pull on the line 11 by thevessel V, as the vessel moves downward, and in the other direction, asthe vessel rises on a wave, the tension on line 11 remainingsubstantially constant at the value established for the slip clutchmeans SC.

With the load hoist line thus moving with the vessel V, the line 10 maybe raised or lowered, whether or not connected to the elevator E, by theoperation of the reversible hydraulic motor 106, when the brake means107 is released, whereby the load hoist drum 100 is caused to rotateabout the shaft 80, a motion which is superimposed on the shaft motioncaused by the rise and fall of the vessel V.

To accomplish this, a control valve CV2 is adapted to control the flowof hydraulic motor fluid to the motor means 106 and to the brake means107, and from the motor means to a reservoir. The valve means CV2 has aposition for directing fluid from a suitable pressure source throughconduits ll3b and 113 and to an exhaust to cause motor rotation in onedirection, and another position for directing fluid through the conduits11411 and 114 to cause motor rotation in the other direction. In eitherevent, motor fluid is also supplied to the brake inlet conduit 108 froma shuttle valve SV interposed between the conduits 113 and 114.

For moving the load hoist line 10 independently of the tension line 11,the control valve CV1 is operated to relieve operating air pressure fromthe clutch means 81 and the brake means 135, so that the drum 100 may bedriven independently of the tension hoist means, to raise or lower theload line 10 when it is safely above the vessel V, whether the line 10be loaded or unloaded.

With the foregoing in mind, it will now be understood that the tensionon the tension line 11 caused by the application of a controlled airpressure to the slip clutch means SC is preferably maintained at aconstant value whether or not the load hoist line 10 is supporting aload. Accordingly, load sensing means LS are provided to cause theapplication of a variable air pressure to the slip clutch means SC toadjust the torque capacity of the slip clutch means SC so that thepressure supply to the slip clutch means is decreased, if the tension online 11 tends to increase, or the pressure supply to the slip clutchmeans is increased, if the tension on the line tends to decrease.

Such load sensing means may be any typical devices adapted to sense loadon a line to produce a related signal, such as a load cell of thehydraulic type, as indicated at 150 in FIG. 4. This load cell 150 has apiston 151 which projects from the cylinder 152 and is engaged by aportion 31a of a lever 31b which supports the above described tensionline sheave 31 on the axle 31c, the lever being pivotally mounted on apin 31d carried by the support structure, as is obvious. Leading fromthe load cell cylinder 152 is a conduit 153 which is connected to apressure regulator or transmitter R2 of any suitable type which, as iswell known, is operative to regulate the drop in air pressure suppliedfrom a source 154 and establish an outlet air signal pressure in aconduit 155 which is a function of the applied hydraulic pressure fromthe load sensor means LS. The air pressure from the regulator R2provides a signal which is conducted by the conduit 155 to thecontroller R1 to modify the net output pressure from the controller R1to the slip clutch means SC.

Assuming that the vessel V, with a load thereon, such as certainequipment or personnel to be elevated to the platform P is situated at alocation below the boom B, the tension line 11 is lowered, either firstor with the load line 10, and the tension line 11 is connected to thevessel V. Air is supplied at a controlled value to the slip clutch meansSC causing a tension on the line 11 proportionate to the weight of theelevator E and any load which it is to lift, or proportionate to theload to be lifted if the load is to be engaged by a lift device such asa hook. At this time, the rise and fall of the vessel V will cause thetension drum 45 to oscillate. The motion compensating clutch means 81 isengaged, and the drum shaft brake means 135 correspondingly released, sothat the load hoist drum will oscillate in unison with the tension hoistdrum 45, causing synchronous movement of the load line with the tensionline. corresponding to movement of the vessel. While such synchronousmotion occurs, the load hoist drum motor 106 may be supplied with fluid,and the brake means 107 is released, to enable controlled downwardmovement of the elevator E, or other load support, to the deck of thevessel for loading.

Thereafter, the motor 106 is reversed, causing upward movement of theload relative to the vessel, while the load continues to rise and fallsynchronously with the rise and fall of the vessel. As the load islifted from the deck of the vessel, the load will require an increase inthe torque output of the slip clutch means SC. There is, at the sametime, a resultant tendency to reduce the tension on the tension line 11,which tendency is sensed by the load sensor means 152. The reducedhydraulic signal from the load cell 150 causes a decrease in the airpressure supplied from the transmitter R2 to controller R1 and aresultant increase in the air pressure supplied from the controller R1to the slip clutch means until the torque capacity of the slip clutch SCis sufiicient to not only maintain the initial tension on the line 11,but also to elevate the load, while the motion compensation continues.When the load is at a safe distance above the vessel, and motioncompensation is no longer necessary, the brake means for the load hoistshaft are engaged and the motion compensating clutch means 81 arereleased. At this time, since the slip clutch means SC no longer issubjected to the load, the entire torque from the slip clutch is appliedto the tension drum 45 tending to increase the tension on line 11, butthe load cell will sense the increase in tension, resulting in anincreased hydraulic signal to the transmitter R2 and a reduction in thenet air pressure supplied to the slip clutch means from the controllerR1 to the original value, whereby the tension on line 11 will be heldsubstantially at the constant value through all modes of operation,since the clutch and the hoist means driven thereby are effectively in aclosed loop, feed back system which constantly seeks to maintain aconstant tension on the tension line 10, the system adjusting for loadand increased and decreased tension caused by the rise and fall of avessel relative to a fixed platform, or differences in the rise and fallof two vessels, i.e., relative vertical movement between the twolocations.

The lowering of a load onto the vessel will simply involve reversal ofthe operations described above in elevating a load.

During all of the travel of the elevator E between a location adjacentto the loading platform 26 of the boom B and a location on the deck ofthe vessel V, the sliding connection between the elevator and thetension line 11 provided by the tube 40, will prevent the elevator orother load from spinning on the load line 10. In addition, the load isguided to a precise location on the deck of the vessel, notwithstandingmovement of the vessel beneath the end of the boom.

For the sake of safety, it will be understood that fail safe means (notshown) may be provided. In this connection, it is customary that hoistwinches have normally engaged or spring-set band brakes associated withthe drum, and more particularly with the flange 104 of the hoist drum100 and with the corresponding flange 45a of tensioning hoist drum 45.Such brakes may be also employed in the present apparatus and releasedresponsive to the fluid pressure in the operating system, so that theband brakes would automatically set in the event of loss of pressure inthe system or any portion thereof. The brake on the load hoist drumshould be able to support the maximum load, but the brake on thetensioning hoist drum should be capable of slipping to allow downwardmovement of the vessel.

We claim:

1. A motion compensating hoist including hoist means for moving a loadbetween relatively vertically movable locations comprising: load hoistmeans mounted at one of said locations and having a load lineconnectable to a load, tensioning hoist means mounted at one of saidlocations and having a tension line connectable at the other of saidlocations, a source of power, slip clutch means for connecting saidsource of power to said hoist means to apply tension to said tensionline, motion compensating drive means for connecting said load hoistmeans to said tensioning hoist means for moving said load line and saidtension line synchronously with the relative movement between saidlocations, and means for superimposing on said synchronous movementfurther movement of said load line to move said load relative to saidlocations.

2. A motion compensating hoist as defined in claim 1, includingreleasable drive means in said motion compensating drive means, and aseparate source of power for said load hoist means operable when saidreleasable drive means is released to drive said load hoist means.

3. A motion compensating hoist as defined in claim 2, wherein saidseparate source of power is also operable when said releasable drivemeans is engaged to superimpose said further movement of said load lineon said synchronous movement.

4. A motion compensating hoist as defined in claim 1, wherein said slipclutch means is operable by fluid pressure to transmit torque at a valuewhich varies with the applied fluid pressure, and including means forsupplying pressure fluid to said slip clutch means.

5. A motion compensating hoist as defined in claim 4, wherein said meansfor supplying pressure fluid to said slip clutch means includes tensionresponsive means operable by said tension line for varying the pressureapplied to said fluid pressure operated means to vary the torquetransmitting capacity of said slip clutch means.

6. A motion compensating hoist as defined in claim 4, wherein said meansfor supplying pressure fluid to said slip clutch means includes tensionresponsive means operable by said tension line for varying the pressureapplied tosaid fluid pressure operated means to vary the torquetransmitting capacity of said slip clutch means, said tension responsivemeans including a hydraulic load cell operable by said tension line, andpressure controller means connected to said load cell and responsive tochanges in load on the latter to vary the pressure of pressure fluidsupplied to said slip clutch means.

7. A motion compensating hoist as defined in claim 4, wherein said meansfor supplying pressure fluid to said slip clutch means includes meansfor supplying a selected pressure proportionate to the load to be moved,and means responsive to tension on said tension line to vary thepressure supplied to said slip clutch means, whereby the tension on saidtension line remains substantially constant when said load hoist line issupporting said load and said motion compensating drive means connectssaid tensioning hoist means to said load hoist means and releases saidtensioning hoist means from said load hoist means.

8. A motion compensating hoist as defined in claim 4, wherein said meansfor supplying pressure fluid to said slip clutch means includes pressurecontrol means for applying pressure to said slip clutch means at a valuedetermined by the tension on said tension line.

A motion compensating hoist as defined in claim 1,

wherein said load hoist means includes a drive shaft drivable by saidmotion compensating drive means, and a drum revolvable about said shaft,and including a separate source of power for driving said drum relativeto said shaft.

10. A motion compensating hoist as defined in claim 1, wherein said loadhoist means includes a drive shaft drivable by said motion compensatingdrive means, a drum revolvable about said shaft, and including aseparate source of power for driving said drum relative to said shaft,and releasable means normally connecting said drum to said shaft forrotation as a unit, and means for releasing said releasable means uponoperation of said separate source of power to drive said drum relativeto said shaft.

11. A motion compensating hoist as defined in claim 1, wherein said loadhoist means includes a drive shaft, said motion compensating drive meansincluding a clutch interposed between said tensioning hoist and saidshaft, and actuator means for engaging said last-mentioned clutch.

12. A motion compensating hoist as defined in claim 1, wherein said loadhoist means includes a drive shaft, said motion compensating drive meansincluding a clutch interposed between said tensioning hoist and saidshaft, actuator means for engaging said last-mentioned clutch, brakemeans for said shaft, and actuator means for releasing said brake meanswhen said last-mentioned clutch is engaged.

13. A motion compensating hoist as defined in claim 1, wherein said loadhoist means includes a drive shaft drivable by said motion compensatingdrive means, a drum revolvable about said shaft, and including a motorfor driving said drum relative to said shaft, said motion compensatingdrive means including a clutch interposed between said tensioning hoistand said shaft, actuator means for engaging said last-mentioned clutchmeans, brake means for said shaft, and actuator means for releasing saidbrake means when said last-mentioned clutch is engaged.

14. Drum apparatus for a load line comprising: a drum shaft, a drumrevolvably mounted on said shaft for relative rotation, a support fixedon said shaft for rotation therewith, reversible motor means carried bysaid support and engaged with said drum to rotate the latter in eitherdirection, releasable means carried by said support and engageable withsaid drum to lock said drum to said shaft, means for driving said motorin either direction and releasing said releasable means, and drive meansfor rotating said shaft in either direction.

15. Drum apparatus as defined in claim 14, including brake means forsaid shaft, and means for releasing said brake means when said drivemeans is operative to rotate said shaft.

16. Drum apparatus as defined in claim 14, wherein said drive meansincludes slip clutch means having a pressure responsive actuator forvarying the torque transmitting capacity of said slip clutch means.

17. Drum apparatus as defined in claim 14, wherein said drive meansincludes another drum and shaft connected for rotation with one anotherand having a line, releasable means driven by said another drum andshaft and connectable to said shaft of the first-mentioned drum to driveboth of said drums in unison, and variable slip clutch means for drivingsaid another drum and shaft to apply tension to the line thereon.

Disclaimer 3,675,900.-0ha1'Zes D. Bawon, Huntington Beach, Earl A.Peterson, Long Beach, Gawy K. Starla, Buena Park, and Carl A. Wz'lms, LaHabra, Calif. MOTION COMPENSATING HOIST. Patent dated July 11, $72.Disclaimer filed June 12, 1972, by the assignee, Bywon J ackson,

no. Hereby disclaims the portions of the term of the patent subsequentto Mar. 14, 1989.

[Ofiicial Gazette J anua'r z 30, 1.973.]

1. A motion compensating hoist including hoist means for moving a loadbetween relatively vertically movable locations comprising: load hoistmeans mounted at one of said Locations and having a load lineconnectable to a load, tensioning hoist means mounted at one of saidlocations and having a tension line connectable at the other of saidlocations, a source of power, slip clutch means for connecting saidsource of power to said hoist means to apply tension to said tensionline, motion compensating drive means for connecting said load hoistmeans to said tensioning hoist means for moving said load line and saidtension line synchronously with the relative movement between saidlocations, and means for superimposing on said synchronous movementfurther movement of said load line to move said load relative to saidlocations.
 2. A motion compensating hoist as defined in claim 1,including releasable drive means in said motion compensating drivemeans, and a separate source of power for said load hoist means operablewhen said releasable drive means is released to drive said load hoistmeans.
 3. A motion compensating hoist as defined in claim 2, whereinsaid separate source of power is also operable when said releasabledrive means is engaged to superimpose said further movement of said loadline on said synchronous movement.
 4. A motion compensating hoist asdefined in claim 1, wherein said slip clutch means is operable by fluidpressure to transmit torque at a value which varies with the appliedfluid pressure, and including means for supplying pressure fluid to saidslip clutch means.
 5. A motion compensating hoist as defined in claim 4,wherein said means for supplying pressure fluid to said slip clutchmeans includes tension responsive means operable by said tension linefor varying the pressure applied to said fluid pressure operated meansto vary the torque transmitting capacity of said slip clutch means.
 6. Amotion compensating hoist as defined in claim 4, wherein said means forsupplying pressure fluid to said slip clutch means includes tensionresponsive means operable by said tension line for varying the pressureapplied to said fluid pressure operated means to vary the torquetransmitting capacity of said slip clutch means, said tension responsivemeans including a hydraulic load cell operable by said tension line, andpressure controller means connected to said load cell and responsive tochanges in load on the latter to vary the pressure of pressure fluidsupplied to said slip clutch means.
 7. A motion compensating hoist asdefined in claim 4, wherein said means for supplying pressure fluid tosaid slip clutch means includes means for supplying a selected pressureproportionate to the load to be moved, and means responsive to tensionon said tension line to vary the pressure supplied to said slip clutchmeans, whereby the tension on said tension line remains substantiallyconstant when said load hoist line is supporting said load and saidmotion compensating drive means connects said tensioning hoist means tosaid load hoist means and releases said tensioning hoist means from saidload hoist means.
 8. A motion compensating hoist as defined in claim 4,wherein said means for supplying pressure fluid to said slip clutchmeans includes pressure control means for applying pressure to said slipclutch means at a value determined by the tension on said tension line.9. A motion compensating hoist as defined in claim 1, wherein said loadhoist means includes a drive shaft drivable by said motion compensatingdrive means, and a drum revolvable about said shaft, and including aseparate source of power for driving said drum relative to said shaft.10. A motion compensating hoist as defined in claim 1, wherein said loadhoist means includes a drive shaft drivable by said motion compensatingdrive means, a drum revolvable about said shaft, and including aseparate source of power for driving said drum relative to said shaft,and releasable means normally connecting said drum to said shaft forrotation as a unit, and means for releasing said releasable means uponoperation of said separate source of power to drive sAid drum relativeto said shaft.
 11. A motion compensating hoist as defined in claim 1,wherein said load hoist means includes a drive shaft, said motioncompensating drive means including a clutch interposed between saidtensioning hoist and said shaft, and actuator means for engaging saidlast-mentioned clutch.
 12. A motion compensating hoist as defined inclaim 1, wherein said load hoist means includes a drive shaft, saidmotion compensating drive means including a clutch interposed betweensaid tensioning hoist and said shaft, actuator means for engaging saidlast-mentioned clutch, brake means for said shaft, and actuator meansfor releasing said brake means when said last-mentioned clutch isengaged.
 13. A motion compensating hoist as defined in claim 1, whereinsaid load hoist means includes a drive shaft drivable by said motioncompensating drive means, a drum revolvable about said shaft, andincluding a motor for driving said drum relative to said shaft, saidmotion compensating drive means including a clutch interposed betweensaid tensioning hoist and said shaft, actuator means for engaging saidlast-mentioned clutch means, brake means for said shaft, and actuatormeans for releasing said brake means when said last-mentioned clutch isengaged.
 14. Drum apparatus for a load line comprising: a drum shaft, adrum revolvably mounted on said shaft for relative rotation, a supportfixed on said shaft for rotation therewith, reversible motor meanscarried by said support and engaged with said drum to rotate the latterin either direction, releasable means carried by said support andengageable with said drum to lock said drum to said shaft, means fordriving said motor in either direction and releasing said releasablemeans, and drive means for rotating said shaft in either direction. 15.Drum apparatus as defined in claim 14, including brake means for saidshaft, and means for releasing said brake means when said drive means isoperative to rotate said shaft.
 16. Drum apparatus as defined in claim14, wherein said drive means includes slip clutch means having apressure responsive actuator for varying the torque transmittingcapacity of said slip clutch means.
 17. Drum apparatus as defined inclaim 14, wherein said drive means includes another drum and shaftconnected for rotation with one another and having a line, releasablemeans driven by said another drum and shaft and connectable to saidshaft of the first-mentioned drum to drive both of said drums in unison,and variable slip clutch means for driving said another drum and shaftto apply tension to the line thereon.